5 Answers
5

+1 good recommendations and package links. In general, it is better to say "Check out how-to-monitor-your-servers-with-snmp-and-cacti at debuntu.org" rather than "this link" as it is more descriptive and doesn't break if debuntu.org goes off the net.
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mswDec 24 '10 at 15:53

karthick87 has the answer, but just to amplify it your monitoring has to be distributed amongst the 300 end-stations and cannot be simply centralized to one point.

The biggest reason this is necessary is that you are probably using a switched (not shared) network hub so no single point is capable of seeing all the traffic on the net. SNMP is certainly old-school, partly because it works.